Fix various typos

Correct an assortment of typos throughout the code base.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Matthew Ahrens <mahrens@delphix.com>
Reviewed-by: Ryan Moeller <ryan@iXsystems.com>
Signed-off-by: Andrea Gelmini <andrea.gelmini@gelma.net>
Closes #11774

module/os/linux/zfs/zfs_vnops_os.c

@@ -3140,7 +3140,7 @@ top:
 
 	/*
 	 * Create a new object for the symlink.
-	 * for version 4 ZPL datsets the symlink will be an SA attribute
+	 * for version 4 ZPL datasets the symlink will be an SA attribute
 	 */
 	zfs_mknode(dzp, vap, tx, cr, 0, &zp, &acl_ids);
 

module/os/linux/zfs/zfs_znode.c

@@ -217,7 +217,7 @@ zfs_znode_fini(void)
  * created or destroyed.  This kind of locking would normally reside in the
  * znode itself but in this case that's impossible because the znode and SA
  * buffer may not yet exist.  Therefore the locking is handled externally
- * with an array of mutexs and AVLs trees which contain per-object locks.
+ * with an array of mutexes and AVLs trees which contain per-object locks.
  *
  * In zfs_znode_hold_enter() a per-object lock is created as needed, inserted
  * in to the correct AVL tree and finally the per-object lock is held.  In

module/os/linux/zfs/zio_crypt.c

@@ -115,7 +115,7 @@
  * Similarly to ZIL blocks, the core part of each dnode_phys_t needs to be left
  * in plaintext for scrubbing and claiming, but the bonus buffers might contain
  * sensitive user data. The function zio_crypt_init_uios_dnode() handles parsing
- * which which pieces of the block need to be encrypted. For more details about
+ * which pieces of the block need to be encrypted. For more details about
  * dnode authentication and encryption, see zio_crypt_init_uios_dnode().
  *
  * OBJECT SET AUTHENTICATION: